Restored with_metaclass [skip CI]
Restored with_metaclass [skip CI]


Former-commit-id: c2a33197efb92ada493ce357df41250a118a7f16 [formerly cfc8d04ed82706a245c77bf3493dd4ae437458c4]
Former-commit-id: 4c042f754cc61321f59c2807a0dd99893c1876c8
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine